Synthesis of polycylic aromatic heterocyclic compounds via thermal isomerizations of 1,8-diarylethynylnaphthalenes

Article abstract of DOI:10.1007/PL00010114

The palladium catalyzed reaction between 1,8-diiodonaphthalene and ethynylarenes affords 1,8-Bis(heteroarylethynyl)naphthalenes which can cyclize thermally via diradical intermediates to the corresponding heterocyclic acenaphthene derivatives in high yiel

Full text of DOI:10.1007/PL00010114

Monatshefte fuÈr Chemie 129, 1035±1048 (1998)
Synthesis of Polycylic Aromatic Heterocyclic
Compounds via Thermal Isomerizations
of 1,8-Diarylethynylnaphthalenes
Ã
Thomas Eckert and Junes Ipaktschi
Institute of Organic Chemistry, Justus Liebig University, D-35392 Giessen, Germany
Summary. The palladium catalyzed reaction between 1,8-diiodonaphthalene and ethynylarenes
affords 1,8-Bis(heteroarylethynyl)naphthalenes which can cyclize thermally via diradical inter-
mediates to the corresponding heterocyclic acenaphthene derivatives in high yields.
Keywords. Thermal cyclization; Diradicals; Aromatic heterocyclic compounds; Alkynes; Palladium
catalyzed cross coupling reactions.
Synthese von polycyclischen heteroaromatischen Verbindungen durch thermische
Isomerisierung von 1,8-Diarylethinylnaphthalinen
Zusammenfassung. Es wurden uÈber eine palladiumkatalysierte Reaktion zwischen 1,8-
Diiodnaphthalin und Ethinylarenen 1,8-Bis(heteroarylethinyl)naphthaline hergestellt, welche
thermisch uÈber eine Diradikalzwischenstufe in hohen Ausbeuten zu den entsprechenden
Acenaphthenderivaten cyclisieren.
Introduction
In extension of our work on thermal isomerizations of diarylethynylnaphthalenes
to polycyclic aromatic compounds [1], we have investigated the thermolysis of
different 1,8-bis(heteroarylethynyl)naphthalenes to the corresponding acenaphtho-
chinolines, -isochinolines, -benzofuranes, and -chinazolines. In this paper we
describe a convenient synthesis of these polycyclic heteroaromatic compounds.
Results and Discussion
Synthesis of 1,8-bis(heteroarylethynyl)naphthalenes 3a±c, 4a,b, and 5a±d
The 1,8-bis(heteroarylethynyl)naphthalenes 3a±c, 4a,b, and 5a±d (Scheme 2) were
prepared in high yield via a palladium catalyzed coupling reaction of 1,8-diiodona-
phthalene (2) with the terminal alkynes 1a±e under Sonogashira conditions [2]
Ã
Corresponding author

1036
T. Eckert and J. Ipaktschi
Scheme 1
Scheme 2
(Scheme 1). In all cases, triethylamine was used as base and simultaneously as
solvent in the presence of Pd[P(Ph)3]2Cl2/CuI as catalyst.
Treatment of 1 equivalent of 2 with 2.2 equivalents of 5-ethynylpyrimidine
(1a), 3-ethynylpyridine (1b), or 3-ethynyl-4-trimethylsilylfuran (1c), respectively,
resulted in the symmetrically substituted naphthalene derivatives 3a±c in 35±97%
yield as colorless crystalline compounds. The unsymmetrically substituted
naphthalenes 5a±d were synthesized similarly via two consecutive coupling
reactions of 1,8-diiodonaphthalene (2) with terminal alkynes. In the ®rst step, 2 is

Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
1037
Table 1. Preparation of mono- and dialkynylated naphthalenes 3a±c, 4a,b, and 5a±d from the iodo-
naphthalenes 2 and 4a,b and from the corresponding terminal alkynes 1a±e via palladium catalyzed
reactionsa
iodonaphthalene
alkyne
time (h)
product
yield (%)
2
1a
1b
1c
1b
1c
1d
1b
1e
1e
48
48
48
36
48
48
48
48
36
3a
3b
3c
4a
4b
5a
5b
5c
5d
35
82
97
54
69
89
86
95
80
2
2
2
2
4a
4b
4a
4b
a All reactions were carried out in triethylamine at 25ꢀC under argon with 2 mol% Pd[P(C6H5)3]2Cl2
and 4 mol% CuI (referred to alkyne) as catalyst using of 1 eq. aryliodide and 1.2 eq. of the alkyne
(monoalkynylation) or 2.2 eq. of the alkyne (dialkynylation), respectively
transformed to the 1-heteroarylethynyl-8-iodonaphthalnes 4a,b using the alkynes
1b and 1c in 69% and 54% yield, respectively. In a subsequent step, 4a and 4b are
converted in high yields to 5a and 5b, respectively, by coupling with alkynes 1b
and 4-ethynylanisole (1d). The results are summarized in Table 1.
For the synthesis of diethynylnaphthalene 3c, the required 3-ethynyl-4-tri-
methylsilylfuran (1c) was prepared by desilylation of 1-((4-trimethylsilyl)-3-furanyl)-
2-trimethylsilylacetylene (6) (Scheme 3). During the desilylation experiments we
found that tetrabutylammonium¯uoride (TBA-F) in dichloromethane as solvent
could be used as a convenient reagent for selective removal of the trimethylsilyl
group from the C:C-bond. After 5 min, alkyne 1c was generated in 74% yield.
Prolongation of the reaction for further 48 h caused no cleavage of the
trimethylsilyl group on the furan ring. Contradictory to this observation, in THF
as solvent both trimethylsilyl groups on the C:C-bond as well as on the furan ring
of 6 were replaced by hydrogen to afford 3-ethynylfuran (7) within 1 h.
Scheme 3

1038
T. Eckert and J. Ipaktschi
Thermal cyclization reaction of naphthalene derivatives 3a±c and 5a,b
The 1,8-bis(heteroarylethynyl)naphthalenes 3a±c and 5a,b were converted to their
corresponding acenaphthene derivatives by heating in organic solvents such as
toluene or DMSO to 125ꢀC and 150ꢀC, respectively. The cyclization of 3a±c and
5a,b in toluene afforded the acenaphthene derivatives 8±12 (Scheme 4) in 67±99%
yield. In addition, the thermal isomerization of substituted naphthalene derivatives
3b and 5a led to a mixture of the heterocyclic by-products 13±15 in 7±23% yield.
In DMSO as solvent, also the thio compounds 16±18 were formed in 3±5% yield
by isomerization of 3a,b and 5a. All acenaphthenes were characterized by their
spectra (see experimental section). The results are summarized in Table 2.
To study the thermal isomerization of naphthalene derivatives with an aromatic
and a non-aromatic substituent at the C:C-bond, we synthesized compounds 5c
and 5d via a palladium catalyzed reaction of 4a and 4b with trimethylsilylace-
Scheme 4

Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
1039
Table 2. Thermal cyclization of 1,8-(arylethynyl)naphthalenes 3a±c, 5a±d, and 1f to acenaphthenes
8±18 in DMSO
1,8-(arylethynyl)-
naphthalene
T (ꢀC)
time (h)
product(s) (%)
3a
3b
3c
5a
5b
5c
5d
1f
150
150
130
140
125
185
185
90
9
4
8 (92), 16 (5)
9 (68), 13 (23), 17 (5)
10 (99)
2,5
7,5
2,5
10
10
10
11 (67), 14 (20), 15 (7), 18 (3)
12 (97)
no reaction
no reaction
decomposition
tylene (1e) and 1f by removal of the acetylenic trimethylsilyl group from 5d.
Interestingly, in spite of the high temperature of 185ꢀC no thermal cyclization of 5c
and 5d occurred. Instead, compound 1f decomposed at 90ꢀC.
The results reported in this work reveal a mechanism via diradical
intermediates for the thermal cyclization of 1,8-diarylethynylnaphthalenes. This
is discussed here exemplarily for the isomerization of 3b to 9 and 13 via diradicals
19±21 (Scheme 5). In the intermediate 19, formed in the ®rst step of the reaction,
the two radical centers are sp-hybridized, and each electron is delocalized over one
pyridine ring. In 20 and 21, respectively, one of the electrons is localized in a sp2-
orbital, and the other one is delocalized in an aza pentadienyl system. In the
Scheme 5

1040
T. Eckert and J. Ipaktschi
following step, diradicals 20 and 21 are stabilized by transfer of a hydrogen atom
(presumably by abstraction and readdition) to give products 9 and 13 (ratio 3:1).
This ratio seems to be characteristic for radical addition to position 2 versus 4 of a
pyridine ring [3] and was also found by cyclization of the naphthalene derivative
5a to the acenaphthenes 14 and 15. The resonance stabilization of the diradicals
during the isomerization of the naphthalene derivatives 3a±c, 5a, and 5b is
responsible for the thermal cyclization at relative low temperatures. The lack of
thermal isomerization of naphthalene derivatives 5c, 5d, or 1f is attributed to the
lower resonance stabilization energy of their corresponding intermediates.
Because of the electrophilicity of the radical intermediates, the thermolysis of
the unsymmetrically naphthalene derivative 5a leads to benzo[k]¯uoranthene 11 as
a major product and the pyrolysis of 5b exclusively to acenaphthobenzofuran 12.
The formation of 16±18 from the thermolysis of 3a,b and 5a could be ex-
plained by the trapping of a thiomethoxy group from DMSO by the corresponding
diradical intermediates.
Experimental
General
All reactions were carried out under argon with dried solvents. Elemental analyses: Carlo Erba
1
Modell 1104; IR: Bruker IFS 25; UV: Hewlett-Packard 8452A diode array spectrophotometer; H
and 13C NMR: Bruker AM 400 resp. AC 200; MS: Varian MAT 311A resp. Varian MAT 111;
melting points: BuÈchi SMP-20. Trimethylsilylacetylene [4], 3-ethynylpyridin [5], 4-ethynylanisol
[6], bis(triphenylphosphanyl)palladium(II) chloride [7], 1,8-diiodonaphthalene [8], and 1-((4-tri-
methylsilyl)-3-furanyl)-2-trimethylsilylacetylene [9] were prepared by known procedures. 5-Bromo-
pyrimidine was purchased from Aldrich.
1-(5-Pyrimidyl)-2-trimethylsilylacetylene
To a solution of 1.59 g (10 mmol) 5-bromopyrimidine and 1.18 g (12 mmol) trimethylsilylacetylene
in triethylamine (30 ml), Pd[P(C6H5)3]2Cl2 (168 mg, 0.24 mmol ˆ 2 mol%) and CuI (92 mg,
0.48 mmol ˆ 4 mol%) were added. The reaction was carried out in an autoclave at 80ꢀC. After
removal of the solvent, the residue was extracted with diethyl ether. Subsequently, the ®ltered
solution was evaporated, and the crude product was puri®ed by distillation at 65ꢀC and 5 torr to yield
1.73 g (98%) of colorless crystals.
M.p.: 33ꢀC; IR (®lm): ꢀ~ ˆ 3042, 2960, 2900, 2166, 1571, 1543, 1250, 864, 845 cmꢁ1; UV
(ethanol): ꢁmax (lg") ˆ 240 (4.16), 250 (4.26), 258 (4.11) nm; 1H NMR (400 MHz, CDCl3): ꢂ ˆ 0.25
(s, 9H), 8.75 (s, 2H), 9.10 (s, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ0.40 (3ÂCH3), 97.60
(C), 102.75 (C), 119.51 (C), 156.73 (CH), 158.99 (2ÂCH) ppm; MS (70 eV): m/z (%) ˆ 176 (28)
‡
[M ], 161 (100); HRMS: calcd.: 176.0770 found 176.0775 (HRMS); C9H12N2Si (176.30); calcd.: C
61.32, H 6.86, N 15.89; found: C 61.28, H 6.64, N 15.87.
General procedure for the preparation of 5- ethynylpyrimidine (1a),
3-ethynyl-4-trimethylsilylfuran (1c), and 1-ethynyl-8-((4-trimethylsilyl)-
3-furanylethynyl)naphthalene (1f) from their 1-aryl-2-trimethylsilylacetylenes
To a solution of the 1-aryl-2-trimethylsilylacetylene (1-(5-pyrimidyl)-2-trimethylsilylacetylene,
1-((4-trimethylsilyl)-3-furanyl)-2-trimethylsilylacetylene, and 5d) (10 mmol) in dichloromethane

Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
1041
(20 ml) TBA-F Á 3H2O (tetrabutylammonium¯uoride, 3.465 g, 11 mmol) at 0ꢀC in dichloromethane
(20 ml). Then the mixture was stirred at 25ꢀC for 5 min. Subsequently, the mixture was washed with
water. After drying over MgSO4, 1a and 1c were distilled. The naphthalene derivative 1f was puri®ed
by silica gel column chromatography.
5-Ethynylpyrimidine (1a)
Yield: 0.916 g (88%); colorless crystals after distillation at 100ꢀC and 100 torr; m.p.: 79.5ꢀC; IR
(KBr): ꢀ~ ˆ 3323, 3169, 2104, 1616, 1577, 1546, 1224, 1178, 718 cmꢁ1; UV (ethanol): ꢁmax
(lg") ˆ 238 (3.98) nm; 1H NMR (400 MHz, CDCl3): ꢂ ˆ 3.45 (s, 1H), 8.84 (s, 2H), 9.20 (s, 1H) ppm;
13C NMR (100 MHz, CDCl3): ꢂ ˆ 76.87 (C), 84.39 (CH), 118.71 (C), 157.21 (CH), 159.27 (2ÂCH)
‡
ppm; MS (70 eV): m/z (%) ˆ 104 (49) [M ], 77 (11), 49 (100); HRMS: calcd.: 104.0374, found:
104.0354; C6H4N2 (104.11); calcd.: C 69.22, H 3.87, N 26.91; found: C 69.19, H 3.63, N 27.08.
3-Ethynyl-4-trimethylsilylfuran (1c)
Yield: 1.624 g (74%); colorless oil after distillation at 90ꢀC and 15 torr; ± IR (®lm): ꢀ~ ˆ 3320, 3150,
2960, 2900, 2110, 1510, 1250, 1130, 850, 810 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 206 (3.72), 226
(3.62) nm; 1H NMR (400 MHz, CDCl3): ꢂ ˆ 0.29 (s, 9H), 3.07 (s, 1H), 7.22 (d, J ˆ 1.4 Hz, 1H), 7.69
(d, J ˆ 1.4 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ1.23 (3ÂCH3), 76.33 (CH), 79.95 (C),
‡
110.08 (C), 121.19 (C), 147.29 (CH), 147.52 (CH) ppm; MS (70 eV): m/z (%) ˆ 164 (27) [M ], 149
(100); HRMS: calcd.: 164±0657, found: 164.0658; C9H12OSi (164.28); calcd.: C 65.80, H 7.36;
found C 65.52, H 7.55.
1-Ethynyl-8-((4-trimethylsilyl)-3-furanylethynyl)naphthalene (1f)
Yield: 2.862 g (91%); light yellow oil after silica gel column chromatography (pentane); IR (®lm):
ꢀ~ˆ 3296, 3090, 2955, 2897, 2166, 1572, 1511, 1501, 1249, 842, 826, 766 cmꢁ1; UV (ethanol): ꢁmax
(lg") ˆ 208 (4.17), 236 (4.28), 286 (3.42), 324 (3.75), 336 (3.79), 346 (3.67) nm; 1H NMR
(400 MHz, CDCl3): ꢂ ˆ 0.35 (s, 9H), 3.45 (s, 1H), 7.31 (d, J ˆ 1.4 Hz, 1H), 7.40±7.48 (m, 2H), 7.74±
7.86 (m, 5H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ0.93 (3ÂCH3), 83.71 (C), 83.90 (CH), 89.30
(C), 91.81 (C), 112.10 (C), 119.73 (C), 120.86 (C), 121.08 (C), 125.44 (CH), 125.65 (CH), 129.48
(CH), 130.14 (CH), 131.70 (C), 133.85 (CH), 134.05 (C), 135.87 (CH), 145.60 (CH), 147.46 (CH)
‡
ppm; MS (70 eV): m/z (%): 314 (53) [M ], 299 (100), 239 (91), 73 (87); HRMS: calcd.: 314.1127,
found 314.1102; C21H18OSi (314.46); calcd.: C 80.21, H 5.77; found: C 80.43, H 5.87.
General procedure for the preparation of the symmetric 1,8-dialkynylated naphthalenes 3a±c
from 2 and the corresponding ethynylarenes 1a±c
To a solution of 1,8-diiodonaphthalene (2) (10 mmol) and of the alkyne 1a±c (21 mmol) in triethyl-
amine (20 ml) a catalyst mixture of Pd[P(C6H5)3]2Cl2 (280 mg, 2 mol%) and CuI (152 mg, 4 mol%)
was added at 25ꢀC. The obtained mixture was stirred for 48 h (see Table 1). Subsequently, the
triethylamine was evaporated, and the residue was extracted with diethyl ether. The crude products
were puri®ed by silica gel column chromatography.
1,8-Bis-(5-pyrimidylethynyl)naphthalene (3a)
Yield: 1.992 g (60%); light yellow crystals after silica gel column chromatography (diethyl ether);
m.p.: 195ꢀC; IR (KBr): ꢀ~ˆ 3027, 2208, 1542, 1416, 829, 764, 723, 635 cmꢁ1; UV (ethanol): ꢁmax
(lg") ˆ 238 (4.67), 263 (4.28), 340 (4.29) nm; 1H NMR (400 MHz, CDCl3): ꢂ ˆ 7.53 (dd, J ˆ 7.2 Hz,

1042
T. Eckert and J. Ipaktschi
8.3 Hz, 2H), 7.92 (dd, J ˆ 1.0 Hz, 7.2 Hz, 2H), 7.97 (dd, J ˆ 1.0 Hz, 8.3 Hz, 2H), 8.66 (s, 4H), 9.03
(s, 2H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 89.31 (2ÂC), 96.51 (2ÂC), 119.02 (2ÂC), 119.93
(2ÂC), 125.89 (2ÂCH), 130.98 (2ÂCH), 131.11 (C), 134.01 (C), 135.55 (2ÂCH), 156.73 (2ÂCH),
‡
158.08 (4ÂCH) ppm; MS (70 eV): m/z (%) ˆ 332 (14) [M ], 304 (7), 277 (41), 206 (59), 152 (57),
98 (100); HRMS: calcd.: 332.1062, found: 332.0990; C22H12N4 (332.34); calcd.: C 79.50, H 3.64, N
16.86; found: C 79.90, H 3.24, N 16.86.
1,8-Bis-(3-pyridylethynyl)naphthalene (3b)
Yield: 2.706 g (82%); light yellow crystals after silica gel column chromatography (diethyl ether);
m.p.: 123.5ꢀC; IR (KBr): ꢀ~ˆ 3060, 2220, 1590, 1565, 1485, 840, 810, 780, 710 cmꢁ1; UV (ethanol):
1
ꢁmax (lg") ˆ 240 (4.45), 262 (4.15), 340 (4.24) nm; H NMR (400 MHz, CDCl3): ꢂ ˆ 7.02 (ddd,
J ˆ 0.8 Hz, 4.2 Hz, 7.9 Hz, 2H), 7.45±7.50 (m, 2H), 7.51±7.56 (m, 2H), 7.84±7.89 (m, 4H), 8.40 (dd,
J ˆ 1.6 Hz, 4.9 Hz, 2H), 8.59±8.62 (m, 2H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 92.80 (2ÂC),
92.94 (2ÂC), 119.83 (2ÂC), 120.63 (2ÂC), 122.63 (2ÂCH), 125.65 (2ÂCH), 130.22 (2ÂCH),
131.34 (C), 133.98 (C), 135.03 (2ÂCH), 137.94 (2ÂCH), 148.28 (2ÂCH), 151.82 (2ÂCH) ppm; MS
‡
(70 eV): m/z (%) ˆ 330 (81) [M ], 329 (94), 45 (100); HRMS: calcd.: 330.1153, found: 330.1106;
C24H14N2 (330.39); calcd.: C 87.25, H 4.27, N 8.48; found: C 87.19, H 4.11, N 8.51.
1,8-Bis-((4-trimethylsilyl)-3-furanylethynyl)naphthalene (3c)
Yield: 4.384 g (97%); colorless crystals after silica gel column chromatography (pentane/
dichloromethane ˆ 10:1); m.p.: 68ꢀC; IR (KBr): ꢀ~ˆ 3060, 2970, 2900, 2220, 1575, 1510, 1260,
950, 800, 760 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 240 (4.23), 284 (3.59), 336 (3.78), 352 (3.75) nm;
1H NMR (400 MHz, CDCl3): ꢂ ˆ 0.32 (s, 18H), 7.24±7.29 (m, 4H), 7.42±7.49 (m, 2H), 7.75±7.85
(m, 4H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ0.11 (6ÂCH3), 89.10 (2ÂC), 91.90 (2ÂC), 111.92
(2ÂC), 121.09 (2ÂC), 121.18 (2ÂC), 125.61 (2ÂCH), 129.38 (2ÂCH), 131.13 (C), 134.15 (C),
‡
134.23 (2ÂCH), 146.56 (2ÂCH), 147.28 (2ÂCH) ppm; MS (70 eV): m/z (%) ˆ 452 (21) [M ], 437
(7), 73 (100); HRMS: calcd.: 452.1628, found: 452.1641; C28H28O2Si2 (452.70); calcd.: C 74.29, H
6.23; found: C 74.33, H 6.04.
General procedure for the preparation of 1-(arylethynyl)-8-iodonaphthalenes 4a,b from 2
and the corresponding ethynylarene
To a solution of 2 (3.80 g, 10 mmol) and of alkyne 1b,c (12 mmol) in triethylamine (20 ml), a catalyst
mixture of Pd(P(C6H5)3)2Cl2 (140 mg, 2 mol%) and CuI (76 mg, 4 mol%) was added. The obtained
mixture was stirred between 36 h and 48 h, respectively (see Table 1). Subsequently, the triethyl-
amine was evaporated and the residue extracted with diethyl ether. The crude products wee puri®ed
by silica gel column chromatography.
1-Iodo-8-(3-pyridylethynyl)naphthalene (4a)
Yield: 1.919 g (54%); colorless crystals after silica gel column chromatography (pentane/dichloro-
methane ˆ 1:1); m.p.: 60ꢀC; IR (KBr): ꢀ~ˆ 3070, 2000, 1585, 1550, 1480, 1030, 830, 770, 710 cmꢁ1
;
1
UV (ethanol): ꢁmax (lg") ˆ 240 (4.35), 278 (3.74), 336 (4.07), 352 (4.01) nm; H NMR (400 MHz,
CDCl3): ꢂ ˆ 7.08±7.14 (m, 1H), 7.31 (ddd, J ˆ 0.6 Hz, 4.9 Hz, 7.9 Hz, 1H), 7.46 (dd, J ˆ 7.3 Hz,
8.0 Hz, 1H), 7.82±7.85 (m, 2H), 7.91±7.94 (m, 2H), 8.30 (dd, J ˆ 1.0 Hz, 7.3 Hz, 1H), 8.58 (dd,
J ˆ 1.6 Hz, 4.9 Hz, 1H) 8.89 (d, J ˆ 1.6 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 92.45 (C),
92.74 (C), 97.37 (C), 121.10 (C), 122.06 (C), 123.11 (CH), 125.43 (CH), 127.23 (CH), 130.21 (CH),
130.97 (CH), 131.92 (C), 134.91 (C), 136.23 (CH), 137.59 (CH), 142.82 (CH), 148.66 (CH), 151.55

Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
1043
‡
(CH) ppm; MS (70 eV): m/z (%) ˆ 355 (100) [M ], 228 (46), 227 (62), 201 (39), 200 (46); HRMS:
calcd.: 354.9869, found: 354.9871; C17H10IN (355.17); calcd.: C 57.49, H 2.84, N 3.94; found: C
57.31, H 2.62, N 4.04.
1-Iodo-8-((4-trimethylsilyl)-3-furanylethynyl)naphthalene (4b)
Yield: 2.873 g (69%); colorless crystals after silica gel column chromatography (pentane/dichloro-
methane ˆ 50:1); m.p.: 64ꢀC; IR (KBr): ꢀ~ˆ 3070, 2960, 2900, 2220, 1600, 1565, 1520, 1135, 860,
820, 770 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 238 (4.51), 334 (4.12), 344 (4.03) nm; 1H NMR
(400 MHz, CDCl3): ꢂ ˆ 0.36 (s, 9H), 7.00±7.06 (m, 1H), 7.31 (d, J ˆ 1.4 Hz, 1H), 7.35±7.39 (m,
1H), 7.70±7.78 (m, 2H), 7.82 (dd, J ˆ 1.2 Hz, 7.1 Hz, 1H), 7.87 (d, J ˆ 1.4 Hz, 1H), 8.25 (dd,
J ˆ 1.2 Hz, 7.3 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ0.84 (3ÂCH3), 91.06 (C), 92.89
(C), 94.34 (C), 112.05 (C), 120.85 (C), 122.97 (C), 125.40 (CH), 127.00 (CH), 130.04 (CH), 130.13
(CH), 131.62 (C), 134.80 (C), 135.13 (CH), 142.57 (CH), 145.73 (CH), 147.44 (CH) ppm; MS
‡
(70 eV) m/z (%) ˆ 416 (100) [M ], 401 (7), 274 (45), 259 (62), 73 (74); HRMS calcd: 416.0093,
found: 416.0076; C19H17IOSi (416.33); calcd.: C 54.81, H 4.11; found: C 54.51, H 3.91.
General procedure for the preparation of the asymmetric 1,8 dialkynlated naphthalenes 5a±d
from 1-iodo-8-heteroarylethynylnaphthalenes 4a,b and the corresponding ethynylarenes
To a solution of 1-iodo-8-(heteroarylethynyl)naphthalene 4a,b (10 mmol) and alkyne 1c±e (12 mmol),
a catalyst mixture of Pd[P(C6H5)3]2Cl2 (140 mg, 2 mol%) and CuI (76 mg, 4 mol%) was added at
25ꢀC in triethylamine (20 ml). The obtained mixture was stirred between 36 h and 48 h, respectively
(see Table 1). Subsequently, the triethylamine was evaporated, and the residue was extracted with
diethyl ether. The crude products were puri®ed by silica gel column chromatography.
1-(4-Anisylethynyl)-8-(3-pyridylethynyl)naphthalene (5a)
Yield: 3.154 g (89%); colorless crystals after silica gel column chromatography (diethyl ether); m.p.:
93ꢀC; IR (KBr): ꢀ~ˆ 3100, 3010, 2970, 2950, 2920, 2850, 2210, 1610, 1575, 1520, 1250, 830, 815,
1
775, 710 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 238 (4.48), 266 (3.61), 326 (4.00), 342 (4.00) nm; H
NMR (400 MHz, CDCl3): ꢂ ˆ 3.76 (s, 3H), 6.64±6.69 (m, 2H), 6.99 (ddd, J ˆ 0.9 Hz, 4.9 Hz, 7.9 Hz,
1H), 7.26±7.31 (m, 2H), 7.44±7.53 (m, 3H), 7.80±7.88 (m, 4H), 8.39 (dd, J ˆ 1.6 Hz, 4.9 Hz, 1H),
8.63±8.65 (m, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 55.24 (CH3) 88.25 (C), 92.96 (C), 93.12
(C), 96.73 (C), 113.74 (2ÂCH), 115.73 (C), 120.12 (C), 121.00 (C), 121.03 (C), 122.53 (CH), 125.49
(CH), 125.72 (CH), 129.37 (CH), 130.15 (CH), 131.50 (C), 132.86 (2ÂCH), 134.11 (C), 134.56
(CH), 135.03 (CH), 138.24 (CH), 147.98 (CH), 151.97 (CH), 159.47 (C) ppm; MS (70 eV) : m/z (%)
‡
ˆ 359 (100) [M ], 344 (22), 315 (36), 158 (38), HRMS: calcd.: 359.1310, found: 359.1310;
C26H17NO (359.42); calcd.: C 86.89, H 4.77, N 3.90; found: C 86.96, H 4.64, N 4.06.
1-(3-Pyridylethynyl)-8-((4-trimethylsilyl)-3-furanylethynyl)naphthalene (5b)
Yield: 3.363 g (86%); colorless crystals after silica gel column chromatography (pentane/diethyl
ether ˆ 1:1); m.p.: 110ꢀC; IR (KBr): ꢀ~ˆ 3049, 2953, 2190, 1560, 1507, 1249, 1116, 843, 827, 788,
1
769 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 240 (4.67), 338 (4.28), 353 (4.18) nm; H NMR (400 MHz,
CDCl3): ꢂ ˆ 0.16 (s, 9H), 6.92 (dd, J = 4.9 Hz, 7.9 Hz, 1H), 7.07 (d, J ˆ 1.4 Hz, 1H), 7.11 (d,
J ˆ 1.4 Hz, 1H), 7.32±7.38 (m, 2H), 7.43±7.47 (m, 1H), 7.62±7.71 (m, 4H), 8.28 (dd, J ˆ 1.4 Hz,
4.9 Hz, 1H), 8.48 (d, J ˆ 1.4 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ1.03 (3ÂCH3), 89.18
(C), 91.83 (C), 93.12 (C), 93.20 (C), 111.88 (C), 120.75 (C), 121.01 (C), 121.05 (2ÂC), 122.49
(CH), 125.53 (CH), 125.73 (CH), 129.55 (CH), 130.11 (CH), 131.43 (C), 134.20 (C), 134.50 (CH),

1044
T. Eckert and J. Ipaktschi
135.05 (CH), 139.25 (CH), 146.25 (CH), 147.42 (CH), 148.22 (CH), 150.15 (CH) ppm; MS (70 eV):
‡
m/z (%) ˆ 391 (41) [M ], 376 (37), 316 (11), 73 (37), 38 (100); HRMS: calcd: 391.1392, found
391.1416; C26H21NOSi (391.55); calcd.: C 79.75, H 5.40, N 3.58; found: C 79.55, H 5.37, N 3.46.
1-(3-Pyridylethynyl)-8-trimethylsilylethynylnaphthalene (5c)
Yield: 2.600 g (80%); colorless crystals after silica gel column chromatography (pentane/diethyl
ether ˆ 5:1); m.p.: 54.5ꢀC; IR (®lm): ꢀ~ˆ 3070, 2970, 2910, 2220, 1590, 1575, 1490, 1260, 870, 770,
1
710 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 240 (4.70), 328 (4.24), 340 (4.26) nm; H NMR (400 MHz,
CDCl3): ꢂ ˆ ꢁ0.01 (s, 9H), 7.28 (dd, J ˆ 4.9 Hz, 7.9 Hz, 1H), 7.38±7.45 (m, 2H), 7.77±7.89 (m, 5H),
8.55 (dd, J ˆ 1.6 Hz, 4.9 Hz, 1H), 8.83 (d, J ˆ 1.3 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3):
ꢂ ˆ ꢁ0.23 (3ÂCH3), 92.87 (C), 93.30 (C), 102.52 (C), 104.99 (C), 119.93 (C), 120.65 (C), 121.32
(C), 123.01 (CH), 125.48 (CH), 125.60 (CH), 129.83 (CH), 130.12 (CH), 130.12 (CH), 131.23 (C),
133.93 (C), 134.74 (CH), 136.75 (CH), 138.31 (CH), 148.51 (CH), 152.22 (CH), ppm; MS (70 eV):
‡
m/z (%) ˆ 325 (100) [M ], 310 (66), 295 (8), 280 (15), 73 (21); HRMS: calcd.: 325.1288, found:
325.1295; C22H19NSi (325.49); calcd.: C 81.18, H 5.88, N 4.30; found: C 80.58, H 5.67, N 4.77.
1-Trimethylsilylethynyl-8-((4-trimethylsilyl)-3-furanylethynyl)naphthalene (5d)
Yield: 3.667 g (95%); colorless crystals after silica gel column chromatography (pentane/diethyl
ether ˆ 5:1); m.p.: 90.5ꢀC; IR (KBr): ꢀ~ˆ 3140, 3070, 2970, 2910, 2220, 2140, 1630, 1570, 1520,
1255, 850, 770 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 238 (4.42), 269 (3.51), 326 (3.89), 342 (3.89) nm;
1H NMR (400 MHz, CDCl3): ꢂ ˆ 0.07 (s, 9H), 0.33 (s, 9H), 7.29 (d, J ˆ 1.5 Hz, 1H), 7.37±7.44 (m,
2H), 7.73±7.82 (m, 5H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ0.96 (3ÂCH3), ꢁ0.02 (3ÂCH3),
89.44 (C), 91.73 (C), 102.37 (C), 104.83 (C), 112.23 (C), 120.86 (C), 120.93 (C), 121.36 (C), 125.44
(CH), 125.53 (CH), 129.45 (CH), 129.67 (CH), 131.37 (C), 134.01 (C), 134.35 (CH), 136.50 (CH),
‡
145.91 (CH), 147.37 (CH) ppm; MS (70 eV): m/z (%) ˆ 386 (31) [M ], 371 (45), 355 (26), 314 (76),
298 (55), 283 (29), 239 (46), 142 (64), 73 (100); HRMS: calcd.: 386.1522, found: 386.1523;
C24H26OSi2 (386.64); calcd.: C 74.56, H 6.78; found: C 74.55, H 6.81.
General procedure for the preparation of acenaphthene derivatives 8±18
from the corresponding 1,8-dialkynylated naphthalenes 3a±c and 5a,b
A solution of the 1,8-dialkynylated naphthalenes 3a±c and 5a,b, respectively, (5 mmol in 20 ml
DMSO) was heated between 2.5 h and 9 h and between 125ꢀC and 150ꢀC (see Table 2). Subse-
quently, the solution was diethyl ether (200 ml), and most of the DMSO was extracted with water
(4Â200 ml) from the etheral phase which was dried over MgSO4. The crude products were puri®ed
by silica gel column chromatography and by HPLC, respectively.
7-(5-Pyrimidyl)acenaphtho[1,2-g]chinazoline (8)
Yield: 1.527 g (92%); light yellow crystals after HPLC (LiChrosorb-NH2-phase (7 mm), tert.butyl-
methyl ether/hexane ˆ 7:3); m.p.: 232ꢀC; IR (KBr): ꢀ~ˆ 3044, 1580, 1569, 1552, 1437, 1414, 1395,
813, 767, 726 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 244 (4.61), 312 (4.61), 344 (3.82), 377 (3.79), 386
1
(3.76) nm; H NMR (400 MHz, CDCl3): ꢂ ˆ 7.19 (d, J ˆ 7.2 Hz, 1H), 7.52 (dd, J ˆ 7.2 Hz, 8.0 Hz,
1H), 7.79 (dd, J ˆ 6.9 Hz, 8.1 Hz, 1H), 7.95 (d, J ˆ 8.1 Hz, 1H), 7.99 (d, J ˆ 8.0 Hz, 1H), 8.18 (d,
J ˆ 6.9 Hz, 1H), 8.48 (s, 1H), 9.05 (s, 2H), 9.28 (s, 1H), 9.52 (s, 1H), 9.54 (s, 1H) ppm; 13C NMR
(100 MHz, CDCl3): ꢂ ˆ 119.01 (CH), 120.51 (CH), 123.91 (CH), 124.50 (C), 127.74 (CH), 127.86
(C), 128.35 (CH), 128.40 (CH), 128.61 (CH), 130.26 (C), 130.44 (C), 134.31 (C), 134.56 (C), 135.51
(C), 139.35 (C), 143.23 (C), 149.04 (C), 155.24 (CH), 158.34 (2ÂCH), 158.42 (CH), 159.95

Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
1045
‡
(CH) ppm; MS (70 eV): m/z (%) ˆ 332 (92) [M ], 331 (100), 304 (38); HRMS: calcd.: 331.0984,
found: 331.0989; C22H12N4 (332.37); calcd.: C 79.50, H 3.64, N 16.86; found: C 79.37, H 3.49,
N 17.05.
7-(3-Pyridyl)acenaphtho[1,2-g]chinoline (9)
Yield: 1.115 g (68%); light yellow crystal after HPLC (SiO2-100, tert.butylmethyl ether/acetonitrile
ˆ 19:1); m.p.: 211ꢀC; IR (KBr): ꢀ~ˆ 3025, 1594, 1571, 1495, 882, 827, 814, 775, 713 cmꢁ1; UV
(ethanol): ꢁmax (lg") ˆ 214 (4.37), 242 (4.48), 298 (4.35), 312 (4.55), 340 (3.77), 352 (3.65), 372
(3.73), 392 (3.64) nm; 1H NMR (400 MHz, CDCl3): ꢂ ˆ 6.85 (d, J ˆ 7.1 Hz, 1H), 7.34±7.40 (m, 2H),
7.55 (dd, J ˆ 5.2 Hz, 7.5 Hz, 1H), 7.65 (dd, J ˆ 7.1 Hz, 8.1 Hz, 1H), 7.78 (d, J ˆ 8.2 Hz, 1H), 7.84 (d,
J ˆ 8.1 Hz, 1H), 7.87±7.93 (m, 1H), 8.03 (d, J ˆ 7.0 Hz, 1H), 8.22 (dd, J ˆ 1.7 Hz, 8.2 Hz, 1H), 8.29
(s, 1H), 8.82±8.86 (m, 3H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 119.53 (CH), 119.64 (CH),
120.89 (CH), 122.91 (CH), 123.53 (CH), 126.82 (CH), 126.93 (CH), 128.06 (CH), 128.07 (2ÂC),
128.18 (CH), 130.34 (C), 132.69 (C), 133.86 (C), 135.42 (C), 136.00 (C), 136.27 (CH), 137.97 (C),
138.11 (CH), 139.18 (C), 147.36 (C), 148.99 (CH), 149.90 (CH), 150.94 (CH) ppm; MS (70 eV): m/z
‡
(%) ˆ 330 (50) [M ], 329 (100), 302 (12); HRMS: calcd.: 330.1157, found; 330.1142; C24H14N2
(330.39); calcd.: C 87.25, H 4.27, N 8.48; found: C 87.20, H 4.03, N 8.41.
7-((4-Trimethylsilyl)-3-furanyl)-10-trimethylsilylacenaphtho[1,2-f]benzofuran (10)
Yield: 2.237 g (99%); colorless crystals after silica gel column chromatography (pentane/diethyl
ether ˆ 1:5); m.p.: 62ꢀC; IR (KBr): ꢀ~ˆ 3070, 2960, 2900, 1620, 1510, 1255, 840, 760 cmꢁ1; UV
(ethanol): ꢁmax (lg") ˆ 234 (4.56), 260 (3.95), 292 (4.48), 302 (4.64), 328 (3.75), 358 (3.77), 374
1
(3.79) nm; H NMR (400 MHz, CDCl3): ꢂ ˆ ꢁ0.17 (s, 9H), 0.44 (s, 9H), 7.31 (d, J ˆ 7.0 Hz, 1H),
7.58 (dd, J ˆ 7.0 Hz, 8.2 Hz, 1H), 7.65 (s, 1H), 7.79 (dd, J ˆ 6.9 Hz, 8.2 Hz, 1H), 7.84 (s, 2H), 7.90
(d, J ˆ 8.2 Hz, 1H), 7.95 (d, J ˆ 8.2 Hz, 1H), 8.15 (d, J ˆ 6.9 Hz, 1H), 8.24 (s, 1H) ppm; 13C NMR
(100 MHz, CDCl3): ꢂ ˆ ꢁ0.97 (3ÂCH3), ꢁ0.51 (3ÂCH3), 113.98 (CH), 114.82 (C), 115.93 (C),
118.89 (CH), 120.24 (C), 122.27 (CH), 122.34 (C), 125.87 (CH), 126.04 (CH), 127.75 (CH), 127.93
(CH), 129.93 (C), 130.49 (C), 133.65 (C), 135.29 (C), 136.18 (C), 136.73 (C), 137.06 (C), 141.05
‡
(CH), 148.96 (CH), 150.36 (CH), 155.43 (C) ppm; MS (70 eV): m/z (%) ˆ 452 (49) [M ], 437 (5),
349 (9), 73 (100); HRMS: calcd.: 452.1629, found: 452.1659; C28H28O2Si2 (452.70); calcd.: C
74.29, H 6.23; found: C 74.37, H 6.34.
7-(3-Pyridyl)-9-methoxybenzo[k]¯uoranthene (11)
Yield: 1.202 g (67%); light yellow crystals after HPLC (SiO2-100, tert.butylmethyl ether/hexane ˆ
3:7); m.p.: 105ꢀC; IR (KBr): ꢀ~ˆ 3040, 2932, 2828, 1615, 1562, 1506, 1430, 1406, 1228, 1220, 1227,
825, 773 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 220 (4.63), 240 (4.73), 274 (4.35), 288 (4.29), 315 (4.75),
1
390 (3.88), 410 (3.87) nm; H NMR (400 MHz, CDCl3): ꢂ ˆ 3.75 (s, 3H), 6.58 (d, J ˆ 7.1 Hz, 1H),
6.80 (d, J ˆ 2.5 Hz, 1H), 7.19 (dd, J ˆ 2.5 Hz, 8.9 Hz, 1H), 7.30±7.38 (m, 1H), 7.60 (dd, J ˆ 4.9 Hz,
7.9 Hz, 1H), 7.65 (dd, J ˆ 7.1 Hz, 8.1 Hz, 1H), 7.74 (d, J ˆ 8.2 Hz, 1H), 7.81 (d, J ˆ 8.1 Hz, 1H),
7.82±7.89 (m, 1H), 7.90 (d, J ˆ 8.9 Hz, 1H), 8.01 (d, J ˆ 6.9 Hz, 1H), 8.32 (s, 1H), 8.79 (d, J ˆ 1.7 Hz,
1H), 8.89 (dd, J ˆ 1.7 Hz, 4.9 Hz, 1H), ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 55.23 (CH3), 105.60
(CH), 117.92 (CH), 118.79 (CH), 120.38 (CH), 121.97 (CH), 124.05 (CH), 126.00 (CH), 126.36
(CH), 127.97 (CH), 128.11 (CH), 128.56 (C), 130.05 (C), 130.32 (CH), 130.38 (C), 134.11 (C),
134.75 (C), 135.12 (C), 135.43 (C), 136.43 (C), 136.57 (C), 136.65 (C), 137.89 (CH), 149.40 (CH),
‡
150.96 (CH), 158.19 (C), ppm; MS (70 eV): m/z (%) ˆ 359 (100) [M ] 344 (23), 157 (21), 84 (52);
HRMS: calcd.: 359.1310, found: 359.1170; C26H17ON (359.42); calcd.: C 86.88, H 4.76, N 3.90;
found: C 87.06, H 4.44, N 3.73.

1046
T. Eckert and J. Ipaktschi
7-(3-Pyridyl)-10-trimethylsilylacenaphtho[1,2-f]benzofuran (12)
Yield: 1.896 g (97%); light yellow crystals after silica gel column chromatography (diethyl ether);
m.p.: 92ꢀC; IR (KBr): ꢀ~ˆ 3043, 2953, 2895, 1610, 1566, 1516, 1254, 840, 822, 773 cmꢁ1; UV
(ethanol): ꢁmax (lg") ˆ 207 (4.57), 236 (4.67), 302 (4.58), 328 (3.87), 373 (3.87) nm; 1H NMR
(400 MHz, CDCl3): ꢂ ˆ 0.45 (s, 9H), 7.12 (d, J ˆ 7.1 Hz, 1H), 7.35 (dd, J ˆ 7.1 Hz, 8.1 Hz, 1H), 7.48
(s, 1H), 7.15±7.95 (m, 1H), 7.64 (dd, J ˆ 7.0 Hz, 8.1 Hz, 1H), 7.74 (d, J ˆ 8.1 Hz, 1H), 7.79 (d,
J ˆ 8.1 Hz, 1H), 7.99±8.06 (m, 2H), 8.10 (s, 1H), 8.78±8.84 (m, 1H), 8.93±9.01 (m, 1H), ppm; 13C
NMR (100 MHz, CDCl3): ꢂ ˆ ꢁ0.68 (3ÂCH3), 114.26 (CH), 115.97 (C), 119.11 (CH), 119.17 (C),
119.70 (C), 121.79 (CH), 123.78 (CH), 126.11 (CH), 126.43 (CH), 127.85 (CH), 127.91 (CH),
130.04 (C), 130.98 (C), 133.65 (C), 134.36 (C), 136.00 (C), 136.40 (C), 136.45 (C), 137.49 (CH),
‡
149.45 (CH), 150.70 (CH), 150.76 (CH), 154.38 (C) ppm; MS (70 eV): m/z (%) ˆ 391 (100) [M ],
376 (60), 73 (14); HRMS: calcd.: 391.1392, found: 391.1401; C26H21ONSi (391.54); calcd.: C
79.75, H 5.40, N 3.58; found: C 79.42, H 5.09, N 3.49.
12-(3-Pyridyl)acenaphtho[1,2-g]isochinoline (13)
Yield: 0.380 g (23%); light yellow crystals after HPLC (SiO2-100, tert.butylmethyl ether/acetonitrile
ˆ 19:1); m.p.: 93ꢀC; IR (KBr): ꢀ~ˆ 3027, 1592, 825, 775, 715 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 246
(4.75), 296 (4.52), 308 (4.63), 342 (3.88), 360 (3.85), 380 (4.07), 402 (4.08) nm; 1H NMR (400 MHz,
CDCl3): ꢂ ˆ 6.78 (d, J ˆ 7.2 Hz, 1H), 7.33 (d, J ˆ 5.9 Hz, 1H), 7.41 (dd, J ˆ 7.2 Hz, 8.1 Hz, 1H), 7.63
(ddd, J ˆ 0.8 Hz, 4.9 Hz, 7.8 Hz, 1H), 7.73 (dd, J ˆ 7.0 Hz, 8.2 Hz, 1H), 7.83±7.88 (m, 2H), 7.91 (d,
J ˆ 8.1 Hz, 1H), 8.14 (d, J ˆ 7.0 Hz, 1H), 8.48 (d, J ˆ 5.9 Hz, 1H), 8.53 (s, 1H), 8.79 (d, J ˆ 1.6 Hz,
1H), 8.93 (dd, J ˆ 1.6 Hz, 4.9 Hz, 1H), 9.39 (s, 1H), ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 118.23
(CH), 119.28 (CH), 119.57 (CH), 122.82 (CH), 123.70 (CH), 126.74 (CH), 127.13 (CH), 127.80 (C),
127.83 (CH), 127.97 (CH), 129.49 (C), 130.05 (C), 132.77 (C), 134.96 (C), 135.11 (C), 135.18 (C),
135.30 (C), 137.39 (CH), 138.30 (C), 139.30 (C), 143.53 (CH), 149.53 (CH), 150.42 (CH),
‡
152.46 (CH), ppm; MS (70 eV): m/z (%) ˆ 330 (100) [M ], 329 (28), 301 (7); HRMS: calcd.:
330.1157, found 330.1180; C24H14N2 (330.39); calcd.: C 87.25, H 4.27, N 8.48; found: C 87.44, H
4.02, N 8.69.
7-(4-Anisyl)acenaphtho[1,2-g]chinoline (14)
Yield: 0.359 g (20%); light yellow crystals after HPLC (SiO2-100, tert.butylmethyl ether/hexane ˆ
3:7); m.p.: 185ꢀC; IR (KBr): ꢀ~ˆ 3041, 2996, 2952, 2832, 1609, 1514, 1491, 1437, 1243, 826, 811,
775 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 216 (4.83), 243 (4.72), 270 (4.11), 312 (4.74), 340 (3.99), 352
(3.90), 372 (3.89), 392 (3.91) nm; 1H NMR (400 MHz, CDCl3): ꢂ ˆ 3.98 (s, 3H), 6.93 (d, J ˆ 7.1 Hz,
1H), 7.16±7.22 (m, 2H), 7.35±7.45 (m, 2H), 7.46±7.52 (m, 2H), 7.69 (dd, J ˆ 6.9 Hz, 8.1 Hz, 1H),
7.80 (d, J ˆ 8.2 Hz, 1H), 7.88 (d, J ˆ 8.1 Hz, 1H), 8.07 (d, J ˆ 6.9 Hz, 1H), 8.25 (dd, J ˆ 1.7 Hz,
8.2 Hz, 1H), 8.30 (s, 1H), 8.91 (dd, J ˆ 1.7 Hz, 4.2 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3):
ꢂ ˆ 55.28 (CH3), 114.37 (2ÂCH), 118.93 (CH), 119.30 (CH), 120.59 (CH), 123.14 (CH), 126.44
(CH), 126.62 (CH), 127.91 (CH), 128.21 (C), 128.25 (CH), 130.17 (C), 130.30 (C), 131.11 (2ÂCH),
135.48 (C), 135.80 (C), 136.26 (CH), 136.46 (C), 136.69 (C), 137.91 (C), 139.07 (C), 147.91 (C),
‡
149.89 (CH), 159.24 (C) ppm; MS (70 eV): m/z (%) ˆ 359 (99) [M ], 358 (100), 344 (12), 315 (27),
158 (36); HRMS: calcd.: 359.1310, found 359.1148; C26H17ON (359.42); calcd.: C 86.88, H 4.76, N
3.90; found: C 86.92, H 4.43, N 3.84.
12-(4-Anisyl)acenaphtho[1,2-g]isochinoline (15)
Yield: 0.126 g (7%); light yellow crystals after HPLC (SiO2-100, tert.butylmethyl ether/hexane ˆ
3:7); m.p.: 187ꢀC; IR (KBr): ꢀ~ˆ 3060, 3033, 2992, 2958, 2916, 2830, 1612, 1594, 1514, 1437, 1250,

Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
1047
823, 775 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 213 (4.49), 247 (4.64), 283 (4.20), 297 (4.39), 308 (4.49),
1
342 (3.77), 360 (3.76), 380 (3.98), 401 (4.00) nm; H NMR (400 MHz, CDCl3): ꢂ ˆ 3.93 (s, 3H),
6.89 (d, J ˆ 7.1 Hz, 1H), 7.14±7.22 (m, 2H), 7.35±7.48 (m, 4H), 7.70 (dd, J ˆ 7.1 Hz, 8.1 Hz, 1H),
7.81 (d, J ˆ 8.2 Hz, 1H), 7.88 (d, J ˆ 8.1 Hz, 1H), 8.10 (d, J ˆ 6.9 Hz, 1H), 8.40±8.50 (m, 2H), 9.34
(s, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 55.43 (CH3), 114.73 (2ÂCH), 118.80 (C), 119.34
(CH), 119.62 (CH), 123.33 (CH), 126.83 (CH), 126.93 (CH), 128.12 (CH), 128.21 (CH), 128.34
(CH), 129.17 (C), 130.35 (C), 130.99 (2ÂCH), 133.82 (C), 135.51 (C), 135.69 (C), 136.17 (C),
136.23 (C), 138.64 (C), 139.21 (C), 143.44 (CH), 152.60 (CH), 159.72 (C) ppm; MS (70 eV): m/z
‡
(%) ˆ 359 (99) [M ], 358 (66), 344 (4), 315 (16), 57 (100); HRMS: calcd.: 359.1310, found
359.1286; C26H17ON (359.42); calcd.: C 86.88, H 4.76, N 3.90; found: C 86.37, H 4.18, N 4.05.
12-Methylthio-7-(5-pyrimidyl)acenaphtho[1,2-g]chinazoline (16)
Yield 0.095 g (5%); light yellow crystals after HPLC (LiChrosorb-NH2-phase 1558, (7 mm),
tert.butylmethyl ether/hexane ˆ 7:3); m.p.: 310ꢀC; Ir (KBr): ꢀ~ˆ 3046, 2919, 2849, 1573, 1430,
1
1411, 1366, 828, 778, 727 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 241 (4.04), 317 (3.93) nm; H NMR
(400 MHz, CDCl3): ꢂ ˆ 2.43 (s, 3H), 7.11 (d, J ˆ 7.2 Hz, 1H), 7.53 (dd, J ˆ 7.2 Hz, 8.1 Hz, 1H), 7.89
(dd, J ˆ 7.2 Hz, 8.0 Hz, 1H), 8.01 (d, J ˆ 8.1 Hz, 1H), 8.06 (d, J ˆ 8.0 Hz, 1H), 9.03 (s, 2H), 9.22 (d,
J ˆ 7.2 Hz, 1H), 9.34 (s, 1H), 9.54 (s, 1H), 10.35 (s, 1H) ppm; 13C NMR (100 MHz, CDCl3):
ꢂ ˆ 19.53 (CH3), 123.97 (CH), 126.18 (CH), 127.00 (C), 128.06 (CH), 128.24 (CH), 128.35 (C),
128.87 (CH), 128.89 (CH), 130.35 (2ÂC), 134.06 (C), 134.69 (C), 135.22 (C), 135.99 (C), 142.16
(C), 143.77 (C), 149.85 (C), 155.23 (CH), 158.30 (2ÂCH), 158.51 (CH), 158.88 (CH) ppm; MS
‡
(70 eV): m/z (%) ˆ 378 (8) [M ]; HRMS: calcd.: 378.0939, found: 378.0922; C23H14N4S (378.46);
calcd.: C 72.99, H 3.73, N 14.80; found: C 73.20, H 3.64, N 14.66.
12-Methylthio-7-(3-pyridyl)acenaphtho[1,2-g]chinoline (17)
Yield: 0.083 g (5%); light yellow crystals after HPLC (SiO2-100, tert.butylmethyl ether/acetonitrile
ˆ 19:1); m.p.: 233ꢀC; IR (KBr): ꢀ~ˆ 3030, 2916, 1599, 1560, 1428, 825, 811, 775, 720 cmꢁ1; UV
(ethanol): ꢁmax (lg") ˆ 246 (4.49), 306 (4.37), 318 (4.58), 344 (3.81), 376 (3.64), 398 (3.61) nm; 1H
NMR (400 MHz, CDCl3): ꢂ ˆ 2.53 (s, 3H), 6.77 (d, J ˆ 7.2 Hz, 1H), 7.39 (dd, J ˆ 7.2 Hz, 8.1 Hz,
1H), 7.53 (dd, J ˆ 4.1 Hz, 8.5 Hz, 1H), 7.59 (dd, J ˆ 2.5 Hz, 4.9 Hz, 1H), 7.78 (dd, J ˆ 7.3 Hz, 8.2 Hz,
1H), 7.84 (d, J ˆ 8.2 Hz, 1H), 7.88±7.95 (m, 2H), 8.78±8.90 (m, 3H), 9.14 (d, J ˆ 7.3 Hz, 1H), 9.20
(dd, J ˆ 1.6 Hz, 8.5 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3): ꢂ ˆ 19.06 (CH3), 121.39 (CH),
123.03 (CH), 123.62 (CH), 125.41 (CH), 127.20 (CH), 127.42 (CH), 127.89 (CH), 128.46 (CH),
129.48 (C), 130.11 (C), 130.11 (C), 133.70 (C), 133.93 (C), 134.53 (CH), 135.42 (C), 135.74 (C),
135.76 (C), 137.96 (CH), 139.52 (C), 141.14 (C), 147.69 (C), 149.18 (CH), 149.88 (CH), 150.88
‡
(CH) ppm; MS (70 eV): m/z (%) ˆ 376 (72) [M ], 375 (100), 360 (33); HRMS: calcd.: 376.1034,
found: 376.0960; C25H16N2S (376.48); calcd.: C 79.76, H 4.29, N 7.44; found: C 79.49, H 4.69,
N 7.24.
7-(4-Anisyl)-12-methylthioacenaphtho[1,2-g]chinoline (18)
Yield: 0.061 g (3%); light yellow crystals after HPLC (SiO2-100, tert.butylmethyl ether/hexane ˆ
3:7); m.p.: 192ꢀC; IR (KBr): ꢀ~ˆ 3062, 2923, 2855, 2836, 1612, 1515, 1486, 1245, 1174, 1041,
909 cmꢁ1; UV (ethanol): ꢁmax (lg") ˆ 219 (4.26), 245 (4.30), 307 (4.14), 317 (4.32), 344 (3.58), 360
1
(3.54), 375 (3.44), 397 (3.36) nm; H NMR (400 MHz, CDCl3): ꢂ ˆ 2.50 (s, 3H), 3.96 (s, 3H), 6.80
(d, J ˆ 7.1 Hz, 1H), 7.14±7.20 (m, 2H), 7.35±7.42 (m, 1H), 7.39±7.46 (m, 2H), 7.51 (dd, J ˆ 4.1 Hz,
8.5 Hz, 1H), 7.72±7.79 (m, 1H), 7.80 (d, J ˆ 8.2 Hz, 1H), 7.91 (d, J ˆ 8.1 Hz, 1H), 8.92 (dd,
J ˆ 1.5 Hz, 4.1 Hz, 1H), 9.11 (d, J ˆ 7.2 Hz, 1H), 9.19 (dd, J ˆ 1.5 Hz, 8.5 Hz, 1H) ppm; 13C NMR

1048
T. Eckert and J. Ipaktschi: Thermal Isomerization of 1,8-Diarylethynylnaphthalenes
(100 MHz, CDCl3): ꢂ ˆ 19.02 (CH3), 55.32 (CH3)), 114.49 (2ÂCH), 121.07 (CH), 123.29 (CH),
125.20 (CH), 126.75 (CH), 127.25 (CH), 127.94 (CH), 128.28 (CH), 128.46 (C), 130.15 (C), 130.16
(C), 131.00 (2ÂCH), 134.59 (2ÂC), 135.78 (C), 136.01 (CH), 136.01 (C), 137.34 (C), 139.49 (C),
‡
141.15 (C), 148.07 (C), 149.80 (CH), 159.35 (C) ppm; MS (70 eV); m/z (%) ˆ 405 (100) [M ], 404
(77), 374 (19); HRMS: calcd.: 404.1109, found 404.1140; C27H19ONS (405.52); calcd.: C 79.97, H
4.72, N 3.45; found: C 79.54, H 4.60, N 3.66.
Acknowledgements
We thank the Fonds der Chemischen Industrie for ®nancial support.
References
[1] Staab HA, Ipaktschi J (1971) Chem Ber 104: 1170
[2] Sonogashira K (1991) In: Trost BM, Fleming I (eds) Comprehensive Organic Synthesis, vol 3.
Pergamon, Oxford, p 521
[3] Hey DH, Stirling CJM, William GH (1955) J Chem Soc 3963
[4] Holmes AB, Sporikou CN (1987) Org Synth 65: 61
[5] Sakamoto T, Shiraiwa M, Kondo Y, Yamanaka H (1983) Synthesis 312
[6] Crisp GT, Flynn BL (1993) J Org Chem 58: 6614
[7] Heck RF (1985) In: Palladium Reagents in Organic Syntheses. Academic Press, London, p 18
[8] House HO, Koepsell DG, Campbell WJ (1972) J Org Chem 37: 1003
[9] Liotta D, Saindane M, Ott W (1983) Tetrahedron Lett 24: 2473
Received February 26, 1998. Accepted (revised) May 4, 1998